public class Example3_1 {
    public static void main (String args[]) {
      char a1 = '十',a2='点',a3 = '进',a4 = '攻';
      char secret = 'A';
      a1 = (char) (a1^secret);
      a2 = (char) (a2^secret);
      a3 = (char) (a3^secret);
      a4 = (char) (a4^secret);
      System.out.println("密文:"+a1+a2+a3+a4);
      a1 = (char) (a1^secret);
      a2 = (char) (a2^secret);
      a3 = (char) (a3^secret);
      a4 = (char) (a4^secret);
      System.out.println("原文:"+a1+a2+a3+a4);
    }
}
